Spoiler warning: In discussing the movie, I have revealed more about the plot than I normally do, including a brief, oblique reference to the ending. Although Shame is not narrative-driven, those who want a "pure" experience may wish to read no further than the first paragraph before seeing the film.

Sexual addiction can be as debilitating a condition as any kind of dependence: drugs, alcohol, gambling, etc. Those afflicted by sexual addiction are compelled by the need to orgasm. It's an all-consuming craving, one that blinds the sufferer to other concerns. For sex addicts, there is no pleasure in the act or its conclusion. They work, sometimes frantically, for the moment of release. Shortly thereafter, it begins anew. It's neither glamorous nor erotic and director Steve McQueen has taken an unflinching and non-judgmental view of sexual addiction in Shame. This is sex without emotion, nudity without titillation, and climaxes without satisfaction. It illustrates how the concept of non-stop sex, a fantasy for many, can be a nightmare for those trapped in this reality.

Brandon Sullivan (Michael Fassbender) is a New York City yuppie who outwardly seems to have it all. His high paying job finances an upscale apartment and lavish nightlife. But he has a secret. For him, sex has become a driving compulsion. His daily routine consists of sneaking into the men's room to masturbate, watching pornography on his work computer, interacting with cam girls on his home laptop, and paying upscale call girls to spend time helping him in his desperate, unending quest for orgasms. He wants no emotional attachment. In fact, he cannot abide it. Sex in a relationship is unthinkable, so he does not date. One night stands are fine, preferably with party girls or the married women with whom he makes eye contact on the subway. His urges are out-of-control but he is able to manage them, at least to the point where no one else is aware - until his needy, emotionally damaged sister, Sissy (Carey Mulligan), moves into his apartment when she has nowhere else to go. The baggage she brings causes Brandon to begin losing his grip.

Shame is essentially a one-character movie: Brandon. Sissy represents a catalyst and we see her through Brandon's eyes. The other two individuals with significant screen time - co-worker Marianne (Nicole Beharie), for whom he develops feelings, and boss David (James Badge Dale) - are important only in the way their interactions impact Brandon's life. The story is about living with the addiction and how it defines his hour-by-hour planning. Others, for example, go to a club hoping to hook up. Brandon, on the other hand, needs to hook up. Failure is not an option. Gradually, however, he begins to realize what a hollow shell his life has become. Not only is he unable to consummate a relationship with a woman he cares about, but his cruel treatment of his sister pushes one too many of her buttons.

Michael Fassbender gives his second standout performance of the year, although more viewers will associate him with X-Men: First Class than with this. His work in Shame is both Oscar-worthy and memorable, with an intensity that can best be described as Brando-esque. He acts with his eyes, his face, his body. Many of his best scenes feature no dialogue, and this is true of the movie as a whole. McQueen speaks as strongly with his camera as with the characters' lines. Especially early in the film, we do not see the faces of Brandon's naked bedmates. When Brandon pads around his apartment naked, his genitalia are framed in the center of the screen (not in close-up). The nudity, which contributed to the MPAA's NC-17 rating, seems more organic than erotic (the possible exception being the playful scene with Marianne and Brandon). It would be disingenuous for the tale of a sex addict not to depict all aspects of the man's life.

Shame is grim, as befits a film about as dark a subject as this one. McQueen invites us to descend into Brandon's world and, once there, he keeps us chained to the character as he struggles through the "filth" (as it is at one point called). Unlike many stories about addiction, this is not one of redemption. The goal is not to depict an artificial narrative, no matter how cathartic, about how Brandon hits bottom then sees the light. Shame ends at a fork in the road; those who despise ambiguous endings will not be pleased by the lack of resolution but anything else would feel like a cheat. Like McQueen's previous outing, Hunger, about the Bobby Sands hunger strike (and which also starred Fassbender), Shame is challenging and difficult, but worth the effort. It's one of those rare movies whose impact is indelible.